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Science M.C.Q

Acids, Bases and Salts · CBSE STD 10 (CBSE - English Medium). 39 questions.

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39 questions · timed · auto-graded

MCQ 11 Mark
The property which is not shown by acids is:
  • A
    They have sour taste.
  • ✓
    They feel soapy.
  • C
    They turn litmus red.
  • D
    Their pH is less than seven.
Answer
Correct option: B.
They feel soapy.
Acids have a sour taste, they turn blue litmus paper red and their pH is less than seven. But they do not feel soapy.
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MCQ 21 Mark
The colour of methyl orange indicator in a solution is yellow. The pH of this solution is likely to be:
  • A
    7
  • B
    Less than 7
  • C
    0
  • ✓
    More than 7
Answer
Correct option: D.
More than 7
Basic or alkaline solutions turn a methyl orange indicator yellow. Thus, the pH of the solution is likely to be more than 7.
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MCQ 31 Mark
The products of chlor$-$alkali process are:
  • A
    $\ce{NaCl, Cl_2}$ and $\ce{H_2}$
  • ✓
    $\ce{H_2, Cl_2}$ and $\ce{NaOH}$
  • C
    $\ce{Cl_2, Na_2CO_3}$ and $\ce{H_2O}$
  • D
    $\ce{NaOH, Cl_2}$ and $\ce{HCl}$
Answer
Correct option: B.
$\ce{H_2, Cl_2}$ and $\ce{NaOH}$
The process of electrolysis of sodium chloride solution is called the chlor$-$alkali process because of the products formed, i.e., $\ce{H_2,Cl_2}$ and $\ce{NaOH}$ . 'Chlor' stands for chlorine and 'alkali' for sodium hydroxide $\ce{(NaOH)}$.
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MCQ 41 Mark
A solution reacts with marble chips to produce a gas which turns lime water milky. The solution contains:
  • A
    $\ce{Na_2SO_4}$
  • B
    $\ce{CaSO_4}$
  • ✓
    $\ce{H_2SO_4}$
  • D
    $\ce{K_2SO_4}$
Answer
Correct option: C.
$\ce{H_2SO_4}$
Marble chips contain calcium carbonate $\left(\ce{CaCO_3}\right)$, which reacts with sulphuric acid $\left( \ce{H_2SO_4} \right)$ to form carbon dioxide gas $\left( \ce{CO_2}\right)$. Carbon dioxide gas, when passed through lime water $\left.\| \ce{Ca(OH)_2}\right]$, turns it milky.
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MCQ 51 Mark
The salt which will give a neutral solution on dissolving in water will be:
  • A
    $\ce{CH_3COONa}$
  • B
    $\ce{NH_4Cl}$
  • ✓
    $\ce{KCl}$
  • D
    $\ce{Na_2CO_3}$
Answer
Correct option: C.
$\ce{KCl}$
$\ce{KCl}$ is formed from a strong acid, hydrochloric acid $\ce{(HCl)}$, and a strong base, potassium hydroxide $\ce{(KOH)}$. On dissolving in water, $\ce{KCl}$ hydrolyses to form equal amounts of $H ^{+}$and $OH ^{-}$ions. This is why an aqueous solution of $\ce{KCl}$ is neutral with a $\ce{pH}$ of almost $7 . \mid$
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MCQ 61 Mark
Which of the following types of medicine is used for treating indigestion caused by over-eating?
  • A
    Antibiotic.
  • B
    Analgesic.
  • ✓
    Antacid.
  • D
    Antiseptic.
Answer
Correct option: C.
Antacid.
Indigestion is caused by the formation of excess acid in the stomach. An antacid is a medicine that is generally a base or a basic salt that neutralises acidity in the stomach.
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MCQ 71 Mark
It has been found that rubbing vinegar on the stung area of the skin of a person gives him relief. The person has been stung by:
  • ✓
    Wasp
  • B
    Ant
  • C
    Honey bee.
  • D
    Nettle leaf hair.
Answer
Correct option: A.
Wasp
When a wasp stings a person, it injects an alkaline solution into the person's skin. This causes high irritation and pain. Applying a weak acid, such as vinegar, to the wound neutralises the alkaline solution and soothes the pain.
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MCQ 81 Mark
The aqueous solution of one of the following salts will turn red litmus to blue. This salt is:
  • A
    Potassium sulphate.
  • B
    Sodium sulphate.
  • C
    Odium chloride.
  • ✓
    Potassium carbonate.
Answer
Correct option: D.
Potassium carbonate.
Potassium carbonate $\left( \ce{K_2CO_3} \right)$ is formed from a weak acid, carbonic acid $\left( \ce{H_2CO_3} \right)$, and a strong base, potassium hydroxide $\ce{(KOH)}$. On hydrolysis, $\ce{K_2CO_3}$ forms more $OH ^{-}$ions than $H ^{+}$ions. Thus, it is basic and therefore turns red litmus blue.
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MCQ 91 Mark
The daffodil plants grow best in a soil having a pH range of 6.0 to 6.5. If the soil in a garden has a pH of 4.5, which substance needs to be added to the soil in order to grow daffodils?
  • A
    Salt.
  • ✓
    Lime.
  • C
    Sand.
  • D
    Compost.
Answer
Correct option: B.
Lime.
If the pH of the soil is 4.5, then it is highly acidic. Thus, soil should be treated with a base, such as quick lime (calcium oxide) or slaked lime (calcium hydroxide). These bases react with the excess acid present in the soil and neutralises it. Thus, the pH of the soil is increased, making it suitable for growing daffodils.
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MCQ 101 Mark
The aqueous solution of one of the following salts will turn phenolphthalein indicator pink. This salt is:
  • A
    $\ce{KCl}$
  • B
    $\ce{K_2SO_4}$
  • ✓
    $\ce{K_2CO_3}$
  • D
    $\ce{KNO_3}$
Answer
Correct option: C.
$\ce{K_2CO_3}$
$\ce{K_2CO_3}$ is formed from a weak acid, carbonic acid $\left( \ce{H_2CO_3} \right)$, and a strong base, potassium hydroxide $\ce{(KOH)}$. On hydrolysis, $\ce{K_2CO_3}$ forms more $OH ^{-}$ions than $H ^{+}$ions, and thus, it is basic. As the aqueous solution of the salt is basic, it turns a phenolphthalein indicator pink.
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MCQ 111 Mark
Fresh milk has a pH of 6. When milk changes into curd, the pH value will:
  • A
    Become 7
  • ✓
    Become less than 6
  • C
    Become more than 7
  • D
    Remain unchanged.
Answer
Correct option: B.
Become less than 6
When fresh milk changes into curd, its acidity increases and it turns sour Therefore, the pH of fresh milk becomes less than 6 when milk changes into curd.
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MCQ 121 Mark
The indicator which produces a pink colour in an alkaline solution is:
  • A
    Methyl orange.
  • B
    Turmeric paper.
  • ✓
    Phenolphthalein.
  • D
    Litmus paper.
Answer
Correct option: C.
Phenolphthalein.
Phenolphthalein produces a pink colour in an alkali solution.
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MCQ 131 Mark
Which of the following is treated with chlorine to obtain bleaching powder?
  • A
    $\ce{CaSO_4}$
  • ✓
    $\ce{Ca(OH)_2}$
  • C
    $\ce{Mg(OH)_2}$
  • D
    $\ce{KOH}$
Answer
Correct option: B.
$\ce{Ca(OH)_2}$
Bleaching powder $\ce{(CaOCl_2)}​​​​​​​$ is formed by passing chlorine gas over slaked lime $[\ce{Ca(OH)_2​​​​​​​​​​​​​​]}.$
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MCQ 141 Mark
A salt is dissolved in water and the $4$ of this salt solution is measured with a universal indicator paper. If the $pH$ of solution is less than $7$, the salt is most likely to be:
  • A
    $\ce{CH_3COONa}$
  • B
    $\ce{Na_2CO_3}$
  • C
    $\ce{KCl}$
  • ✓
    $\ce{NH_4Cl}$
Answer
Correct option: D.
$\ce{NH_4Cl}$
$\ce{NH_4Cl}$ is formed from a weak base, ammonium hydroxide $\left( \ce{NH_4OH} \right)$, and a strong acid, hydrochloric acid $\ce{( HCl )}$. On hydrolysis, $\ce{NH_4Cl}$ forms more $H ^{+}$ions than $OH ^{-}$ions. Thus, it is acidic, with a $pH$ less than $7$ .
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MCQ 151 Mark
The discomfort caused by indigestion due to overeating can be cured by taking:
  • A
    Vinegar.
  • B
    Lemon juice.
  • ✓
    Baking soda.
  • D
    Caustic soda.
Answer
Correct option: C.
Baking soda.
Baking soda, being a base, neutralises the excess acid formed in the stomach and cures the discomfort caused by indigestion.
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MCQ 161 Mark
Bee stings can be treated with:
  • A
    Vinegar.
  • ✓
    Sodium hydrogencarbonate.
  • C
    Potassium hydroxide.
  • D
    Lemon juice.
Answer
Correct option: B.
Sodium hydrogencarbonate.
When a bee stings a person, it injects an acidic solution into the person’s skin, which causes severe pain and an itching sensation. Applying a baking soda solution (sodium hydrogen carbonate solution, which is a base) soothes the pain by neutralising the acid.
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MCQ 171 Mark
A solution turns blue litmus red. Its pH is likely to be:
  • A
    7
  • ✓
    5
  • C
    8
  • D
    14
Answer
Correct option: B.
5
An acidic solution turns blue litmus red. On the pH scale, acids have values less than 7, whereas bases have values greater than 7. Solutions with pH equal to 7 are neutral in nature. Therefore, the pH of the given solution is likely to be 5.
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MCQ 181 Mark
The salt which will give an acidic solution on dissolving in water is:
  • A
    $\ce{KCl}$
  • ✓
    $\ce{NH_4Cl}$
  • C
    $\ce{Na_2CO}$
  • D
    $\ce{CH_3COONa}$
Answer
Correct option: B.
$\ce{NH_4Cl}$
$\ce{NH_4Cl}$ is formed with a weak base, ammonium hydroxide $\left(\ce{NH_4OH} \right)$, and a strong acid, hydrochloric acid $\ce{(HCl).}$ On dissolving in water, $\ce{NH_4Cl}$ hydrolyses to form more $H ^{+}$ions than $OH ^{-}$ions. Thus, it is acidic with a $pH$ less than $7$ .
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MCQ 191 Mark
The number of molecules of water of crystallisation present in washing soda crystals is:
  • A
    Five.
  • B
    Two.
  • ✓
    Ten.
  • D
    Seven.
Answer
Correct option: C.
Ten.
The chemical formula of washing soda is $\ce{Na_2CO_3 \cdot 10 H_2O}$. The water molecules that form part of the structure of a salt are called its water of crystallisation. Hence, the number of molecules of water of crystallisation present in washing soda crystals is $10.$
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MCQ 201 Mark
A solution reacts with zinc granules to give a gas which burns with a $\text{'pop'}$ sound. The solution contains:
  • A
    $\ce{Mg(OH)_2}$
  • B
    $\ce{Na_2CO_3}$
  • C
    $\ce{NaCl}$
  • ✓
    $\ce{HCl}$
Answer
Correct option: D.
$\ce{HCl}$
Zinc granules react with $\ce{HCl}$ to give hydrogen gas, which burns with a $\text{‘pop’}$ sound.
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MCQ 211 Mark
A salt whose aqueous solution will have a $pH$ of more than $7$ will be:
  • ✓
    $\ce{K_2CO_3}$
  • B
    $\ce{K_2SO_4}$
  • C
    $\ce{NaCl}$
  • D
    $\ce{NH_4Cl}$
Answer
Correct option: A.
$\ce{K_2CO_3}$
$\ce{K_2CO_3}$ is formed from a weak acid, carbonic acid $\left( \ce{H_2CO_3} \right)$, and a strong base, potassium hydroxide $\ce{(KOH)}$. On hydrolysis, $\ce{K_2CO_3}$ forms more $OH ^{-}$ions than $H ^{+}$ions. Thus, it is basic, with a $pH$ more than $7$ .
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MCQ 221 Mark
The salt whose aqueous solution will turn blue litmus to red is:
  • ✓
    Ammonium sulphate.
  • B
    Sodium acetate.
  • C
    Sodium chloride.
  • D
    Potassium carbonate.
Answer
Correct option: A.
Ammonium sulphate.
Ammonium sulphate $\ce{\left[\left( NH_4\right)_2SO_4\right]}$ is formed from a weak base, ammonium hydroxide $\ce{\left( NH_4OH \right)}$, and a strong acid, sulphuric acid $\ce{\left(H_2SO_4\right)}$. On dissolving in water, $\ce{\left( NH_4\right)_2SO_4}$ hydrolyses to form more $H ^{+}$ions than $OH ^{-}$ions. As the aqueous solution of the salt $\ce{\left( NH_4\right)_2SO_4}$ is acidic, it turns blue litmus red.
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MCQ 231 Mark
The salt whose aqueous solution will have no effect on either red litmus or blue litmus is:
  • ✓
    Potassium sulphate.
  • B
    Sodium carbonate.
  • C
    Ammonium sulphate.
  • D
    Sodium acetate.
Answer
Correct option: A.
Potassium sulphate.
Potassium sulphate $\ce{\left( K_2SO_4\right)}$ is formed from a strong acid, sulphuric acid $\ce{\left( H_2SO_4\right)}$, and a strong base, potassium hydroxide $\ce{(KOH)}$. On dissolving in water, $\ce{K_2SO_4}$ hydrolyses to form equal amounts of $H ^{+}$and $OH ^{-}$ions. As the salt solution of $\ce{K_2SO_4}$ is neutral, it has no effect on red or blue litmus paper.
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MCQ 241 Mark
Wasp sting contains:
  • A
    A sugar solution.
  • B
    An acidic liquid.
  • C
    A salt solution.
  • ✓
    An alkaline liquid.
Answer
Correct option: D.
An alkaline liquid.
A wasp sting injects an alkaline solution into the skin, which causes high irritation and pain.
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MCQ 251 Mark
The property which is common between vinegar and curd is that they:
  • A
    Have sweet taste.
  • B
    Have bitter taste.
  • C
    Are tasteless.
  • ✓
    Have sour taste.
Answer
Correct option: D.
Have sour taste.
Vinegar and curds are acidic. They both have a sour taste.
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MCQ 261 Mark
Plaster of Paris is prepared by heating one of the following to a temperature of $100^\circ$. This is:
  • A
    $\ce{CaSO_3.2H_2O}$
  • ✓
    $\ce{CaCl_2.2H_2O}$
  • C
    $\ce{CaCO_3.2H_2O}$
  • D
    $\ce{CaSO_4.2H_2O}$
Answer
Correct option: B.
$\ce{CaCl_2.2H_2O}$
When $\ce{CaSO _4\cdot 2 H _2 O} ($gypsum$)$ is heated to a temperature of $100^{\circ} C (373 K)$, it loses three$-$fourths of its water of crystallisation and forms plaster of Paris $( \ce{CaSO_4\cdot 1 / 2 H _2 O}).$
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MCQ 271 Mark
One of the following does not inject an acidic liquid into the skin through its sting. This is:
  • A
    Honey bee.
  • B
    Ant.
  • ✓
    Wasp.
  • D
    Nettle leaf hair.
Answer
Correct option: C.
Wasp.
A honey bee, ant and a nettle leaf hair inject methanoic acid into the skin through their stings. But a wasp injects an alkaline solution into the skin through its sting.
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MCQ 281 Mark
The indicators which turn red in acid solution are:
  • A
    Turmeric and litmus.
  • B
    Phenolphthalein and methyl orange.
  • ✓
    Litmus and methyl orange.
  • D
    Phenolphthalein and litmus.
Answer
Correct option: C.
Litmus and methyl orange.
Litmus and methyl orange turn red in an acid solution.
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MCQ 291 Mark
One of the following salts will give an alkaline solution on dissolving in water. This is:
  • ✓
    $\ce{Na_2CO_3}$
  • B
    $\ce{Na_2SO_4}$
  • C
    $\ce{NaCl}$
  • D
    $\ce{(NH_4)_2 SO_4}$
Answer
Correct option: A.
$\ce{Na_2CO_3}$
$\ce{Na_2CO_3}$ is formed from a weak acid, carbonic acid $\left(\ce{H_2CO_3}\right)$, and a strong base, sodium hydroxide $\ce{( NaOH )}$. On dissolving in water, $\ce{Na_2CO_3}$ hydrolyses to form more $\ce{OH}^{-}$ions than $H ^{+}$ions. Therefore, its solution in water is basic, or alkaline, with a $pH$ more than 7.
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MCQ 301 Mark
The formula of baking soda is:
  • A
    $\ce{K_2CO_3}$
  • B
    $\ce{KHCO_3}$
  • ✓
    $\ce{NaHCO_3}$
  • D
    $\ce{Na_2CO_3}$
Answer
Correct option: C.
$\ce{NaHCO_3}$
The chemical name of baking soda is sodium hydrogen carbonate, and its chemical formula is $\ce{NaHCO_3.}$
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MCQ 311 Mark
Bee sting contains:
  • ✓
    An acidic liquid.
  • B
    A salt solution.
  • C
    An alkaline liquid.
  • D
    An alcohol.
Answer
Correct option: A.
An acidic liquid.
A bee sting contains an acidic solution. The name of the acid is methanoic acid.
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MCQ 321 Mark
One of the following is a medicine for indigestion. This is:
  • A
    Sodium hydroxide.
  • B
    Manganese hydroxide.
  • ✓
    Magnesium hydroxide.
  • D
    Potassium hydroxide.
Answer
Correct option: C.
Magnesium hydroxide.
Magnesium hydroxide, which is a base, acts as an antacid. It neutralises excess acid present in the stomach and cures indigestion. Hence, it is used as a medicine.
 
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MCQ 331 Mark
10mL of a solution of NaOH is found to be completely neutralised by 8mL of a given solution of HCl. If we take 20mL of the same solution of NaOH, the amount of HCl solution (the same solution as before) required to neutralise it will be:
  • A
    4mL
  • B
    8mL
  • C
    12mL
  • ✓
    16mL
Answer
Correct option: D.
16mL
It is given that 10mL of a solution of NaOH is completely neutralised by 8mL of a solution of HCl. Hence, 20mL of the solution of NaOH, which is double the amount taken earlier, will require double the solution of HCl taken earlier, i.e., 16mL, to be completely neutralised.
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MCQ 341 Mark
One of the following is not an organic acid. This is:
  • A
    Ethanoic acid.
  • B
    Formic acid.
  • C
    Citric acid.
  • ✓
    Carbonic acid.
Answer
Correct option: D.
Carbonic acid.

Carbonic acid $\ce{H_2CO_3}$ is formed when $\ce{CO_2}$ is dissolved in water. Hence, carbonic acid is an inorganic or mineral acid. Ethanoic acid, formic acid and citric acid are found naturally.

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MCQ 351 Mark
A solution turns red litmus blue. Its pH is likely to be:
  • A
    1
  • B
    4
  • C
    5
  • ✓
    10
Answer
Correct option: D.
10
A basic solution turns red litmus blue. On the pH scale, bases have values greater than 7, whereas acids have values less than 7. Therefore, the pH of the given solution is likely to be 10.
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MCQ 361 Mark
The acid produced naturally in our stomach is:
  • A
    Acetic acid.
  • B
    Citric acid.
  • ✓
    Hydrochloric acid.
  • D
    Sulphuric acid.
Answer
Correct option: C.
Hydrochloric acid.
Our stomach produces dilute hydrochloric acid naturally. The acid that is produced, which has a pH of around 1.4, does not damage our stomach. Rather, it helps in the digestion of food.
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MCQ 371 Mark
Wasp stings can be treated with:
  • A
    Baking soda.
  • ✓
    Vinegar.
  • C
    Washing soda.
  • D
    Milk of magnesia.
Answer
Correct option: B.
Vinegar.
When a wasp stings a person, it inserts an alkaline solution into the person's skin. This causes high irritation and pain. Applying a weak acid, such as vinegar, to the wound neutralises the alkaline solution and soothes the pain.
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MCQ 381 Mark
A solution turns phenolphthalein indicator pink. The most likely pH of this solution will be:
  • A
    6
  • B
    4
  • ✓
    9
  • D
    7
Answer
Correct option: C.
9
Every substance with a pH greater than 7 is considered basic or alkaline. Basic or alkaline solutions turn phenolphthalein indicator pink. Thus, the pH of the solution is most likely 9.
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MCQ 391 Mark
Which of the following salts will give an aqueous solution having $pH$ of almost $7?$
  • A
    $\ce{NH_4NO_3}$
  • B
    $\ce{NH_4Cl}$
  • C
    $\ce{CaCl_2}$
  • ✓
    $\ce{KCl}$
Answer
Correct option: D.
$\ce{KCl}$

$\ce{KCl}$ is formed from a strong acid, hydrochloric acid $\ce{( HCl )}$, and a strong base, potassium hydroxide $\ce{( KOH )}$ . Thus , $\ce{KCl}$, on hydrolysis, forms equal amounts of $H ^{+}$and $OH ^{-}$ions. This is why an aqueous solution of $\ce{KCl}$ shows a $pH$ of almost $7$ .

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